A camshaft adjuster is used for the targeted adjustment of the phase position between a camshaft and a crankshaft in an internal combustion engine, and thus allows the optimized setting of the valve timing via the engine load and the engine speed. A distinct reduction in the fuel consumption and the exhaust gas emissions as well as increased power of the engine may be achieved in this way.
A camshaft adjuster is usually composed of a stator, a rotor which is positioned in the stator, and two sealing covers. For locking the rotor, one of the sealing covers is often designed as a locking cover having an appropriate locking slide.
In the installed state, the stator is connected in a rotationally fixed manner to a crankshaft, whereas the rotor is connected in a rotationally fixed manner to a camshaft. The stator is designed with a number of pressure chambers which are formed by webs extending radially inwardly away from the stator wall. The rotor mounted inside the stator is positioned with its rotor blades in the stator. The torsion angle of the rotor is delimited by the webs in the stator.
For camshaft adjustment, the pressure chambers may be acted on by a hydraulic medium and thus turn the rotor inside the stator. Due to the torsion of the rotor with respect to the stator, the phase position of the camshaft may be changed, and the opening times of the valves in an internal combustion engine may thus be controlled.
Spring elements are often used to move a rotor back into a neutral or starting position during operation of a camshaft adjuster. These types of spring elements are typically designed in such a way that that they allow the rotor to rotate relative to the stator, so that the rotor may be moved into the desired position inside the stator. A secure fastening of the spring element is necessary to ensure such rotation.
In this regard, a camshaft adjuster of the type mentioned at the outset, having a spring element designed as a torsion spring, is known from DE 10 2009 005 114 A1. The torsion spring is fastened via its two spring ends to spring retainers provided for this purpose, and is situated between a so-called spring cover plate and the sealing cover which is designed as a front cover plate. The spring cover plate is connected to the sealing cover via bolts.
In addition, a device for the variable setting of the timing of gas exchange valves of an internal combustion engine, having a spring element designed as a torsion spring, is known from DE 10 2008 051 732 A1. The torsion spring is situated in a spring chamber, and is fastened via its two spring ends to a sealing cover which is designed as a side cover. The spring chamber is delimited by a pot-shaped snap-on cover, for which purpose the snap-on cover at least partially overlaps the device radially and axially. According to DE 10 2008 051 732 A1, the snap-on cover and the sealing cover are fastened to one another via form-locked elements.
Both of the above-mentioned embodiments allow secure holding of the torsion spring on the sealing cover. However, use of spring cover plates and snap-on covers does not represent a permanent solution for positioning a spring element on a sealing cover due to their weight and the costs associated with manufacture.